The Saints won the championship with a three-pronged running attack, essentially a tailback for every possible situation, the model of specialization. The Colts, who chose Donald Brown last spring to presumably help split the running game, turned largely to Joseph Addai after the former Connecticut standout and first-round draft pick was injured twice during the season.
Although most clubs possess a pretty well-defined feature back, the perception in recent seasons is that success comes principally from having a complementary runner and sharing the load.
But as the 2009 season demonstrated, and the Super Bowl validated, that is only partly true.
"Whatever works best for you," said Saints coach Sean Payton, who clearly believed in spreading the wealth and the carries. "There's really no right or wrong way."
New Orleans was one of three teams in 2009 with three running backs (Pierre Thomas, Mike Bell and Reggie Bush) who rushed for more than 300 yards each. A fourth team, the Cleveland Browns, had a trio of 300-yard rushers, but one of them was Josh Cribbs, who gained most of his yardage as a Wildcat quarterback. The three franchises with a trio of 300-yard backs all qualified for the playoffs.
But of the 12 clubs that had two backs run for more than 500 yards each in 2009, only five went to the playoffs. The Carolina Panthers, just the fifth team in history with a pair of 1,000-yard backs and a club that statistically ranked No. 3 in rushing yards, finished only 8-8. Five of the seven playoff teams that did not have two backs who ran for 500 yards apiece had tailbacks who owned 58 percent or more of their teams' carries (excluding rushes by non-running backs). Three of those teams had individual backs who ran for 1,200 yards or more.
"It's great to have a breather but you want the ball in your hands," said Green Bay tailback Ryan Grant, who had 75.4 percent of the Packers' carries in 2009 and 80.3 percent of their rushing yards.
Still, even though the numbers indicate otherwise, the popular sentiment in the league is that a club requires at least two viable running backs to succeed. And moves made in the offseason -- through free agency, trades and the draft -- suggest that's the overriding approach as teams strive for a one-two punch.
Chicago signed Minnesota free agent Chester Taylor to augment Matt Forte, who might have been overworked during a disappointing '09 sophomore season. The Kansas City Chiefs added Thomas Jones, after the New York Jets released him, to bolster a ground game led by Jamaal Charles, whose résumé includes only 12 career starts. The Jets, who also traded Leon Washington during the draft, signed LaDainian Tomlinson, jettisoned by San Diego, to back up Shonn Greene, whose scintillating playoff performance earned him the starting spot for 2010. Seattle revamped its tailback slot by dealing for both Washington and LenDale White during the draft.
Philadelphia signed Bell, the lone restricted free agent to change teams via an offer sheet, as a partner for second-year pro LeSean McCoy.
In the draft, the Chargers (Ryan Mathews), Bills (C.J. Spiller) and Lions (Jahvid Best) all exercised first-round choices on running backs who should add depth to their respective backfields. The Vikings chose Toby Gerhart in the second round, likely to replace the departed Taylor.
"We had to make a move," said San Diego general manager A.J. Smith, whose lone remaining back of consequence was munchkin-sized Darren Sproles (likely unable to carry a running game on his own, because of his size), and who paid a steep price to move up 16 spots in the first round to nab Mathews with the 12th overall pick.
Can a team have too many solid running backs? Perhaps so. The Dallas Cowboys, for instance, have a difficult time divvying up carries among Felix Jones, Marion Barber and Tashard Choice. Washington, on the other hand, signed free agents Larry Johnson and Willie Parker in the offseason to go with incumbent Clinton Portis. But all three are 29 or older (or will be by the start of the season), none plays special teams and Redskins coaches will have a tough time getting carries for all of them.
There are some franchises in need of a No. 2 runner, it should be pointed out, that made no moves of significance in the offseason and that might go into the '10 season without the kind of two-back model that has become prevalent in the league. Those teams include Cincinnati, Cleveland, Green Bay, Houston, Jacksonville, Pittsburgh and Tennessee.
In a league that increasingly seems to be suggesting you need two to tangle, one could be a lonely number.
"But sometimes you just have to pull the train yourself," said the Bengals' Cedric Benson, who logged 301 of Cincinnati's 452 carries by backs in 2009 and whose relief might have to be located internally. "That's just how it is."
Len Pasquarelli, a recipient of the Pro Football Hall of Fame's McCann Award for distinguished reporting, is a senior writer for ESPN.com.